Looking for small keyswitches to build custom keyboard

[cool-RR]

Hi guys,

I'm looking for a peculiar kind of keyswitch that I really hope exists.

I want a keyswitch with an actuation force of around 40g (allowing 35g-45g), but I want it to be small; I want the width to be around 7mm (allowing between 5mm and 10mm).

For travel distance I want around 2mm.

Would you happen to know where I could get such a keyswitch?


Thanks a lot,
Ram.

[cool-RR]

Please... Anyone? 

[kurplop]

One problem that you'll encounter is finding/making a cap to use with a switch that size. I am attempting to make slightly undersized caps and am using Alps style switches. the 0.50"x0.60" will allow me to make a slightly shorter (front to back) switch. A Cherry switch is 0.55"x0.55". I know that is a lot bigger than what you want but it shows that key switches are typically much bigger than your target dimension.

What is the reason for such a small switch? Are you teaching ferrets to type?

There are plenty of simple on/off switches available. The switches inside a mouse would fall in that size range but you would have to build a somewhat complex mechanism to support the cap. The stem would be too small to secure a cap to it.

You may be forced to consider non mechanical switches.

[cool-RR]

I don't need a cap. I'm willing to use a plain button.

I want something so small so my fingers will need to move the least possible distance. I'm hoping it'll be comfortable to type with. When I type with my regular keyboard I find that I don't lack precision at all, but that the big (read normal) buttons on my keyboard are just a nuisance because they're making me move my fingers way too much.

 The problem I've found with most buttons is that actuation force is way too high. I want 40g-45g and I get much bigger values. Looks like I'm gonna have to get custom springs installed.

[acantha]

You should PM HaaTa. Dude knows a crazy amount regarding keyboard switches. If what you're looking for exists, either he'll know about it or be able to point you at a wiki or another person who does.

[CarVac]

I don't need a cap. I'm willing to use a plain button.

I want something so small so my fingers will need to move the least possible distance. I'm hoping it'll be comfortable to type with. When I type with my regular keyboard I find that I don't lack precision at all, but that the big (read normal) buttons on my keyboard are just a nuisance because they're making me move my fingers way too much.

 The problem I've found with most buttons is that actuation force is way too high. I want 40g-45g and I get much bigger values. Looks like I'm gonna have to get custom springs installed.

If all you want is an undersize keyboard, you could look for replacement keyboards for EEE PC's. I bought a replacement for my 1005HA keyboard for 20 bucks online. Then all you need to do is make a hookup for the flexes to a microcontroller and figure out what the matrix is.

The 1005HA has pretty tactile keys, and the keys are closer together so I find that I don't have to reach nearly as far when using it.

That said, the only reason I needed a replacement was because a key broke, and thus the durability is called into question...

[Moosecraft]

Maybe you should look into microswitches like the ones used in mice.

[miko]

Cherry sells small keyboards.


http://www.amazon.de/Cherry-G84-4100LCMDE-2-Tastatur-USB-schwarz/dp/B000XGXV0C


I'm not sure if this is what you are looking for and I never disassembled one.  I guess this is the closes you can get. I spend a lot of time on research for smaller keyboards (calculator sized) and couldn't find anything.

[dorkvader]

if you are unworried about keycaps, you can just make a custom PCB and space the switches closer together. This may be possible with ml (2mm travel) or mitsumi switches though you'll likely have to modify the switches(ml) or add custom springs (mitsumi) to get an actuation force that low.

Mousefan has some good pictures of mitsumi switches on his website
http://www7.ocn.ne.jp/~hisao/image/burton.htm
finding a keyboard that has mistumi switches will be a little harder, especially in israel.

[cool-RR]

Hi everybody! Thank you all for pitching in and helping!

acantha: Thanks for the connection! I'll PM HaaTa!

CarVac and miko: I'm not looking for small keyboards. I'm looking to build my own custom keyboard, similar to this: http://upload.wikimedia.org/wikipedia/commons/b/b9/Septambic_key_numbering.jpg but with a lot more keys.

dorkvader: I'm going to order a few Cherry ML switches, just to check them out, but I worry that their base is too wide, and that this'll prevent me from being able to pack them close together like I want.

[MTManiac]

what about cherry M8 switches?

[cool-RR]

MTManiac: I've googled for them but couldn't find a datasheet or even pictures. I need to know their specs. And even if they do happen to be a good match for my project...  Aren't they discontinued?

[MTManiac]

http://deskthority.net/photos-videos-f8/yab8433408-s-cherry-switches-t2149.html
deskthority has some good info, that link is just one of many with more information about the m8 switches.
they might be dc'd but you should be able to find them for sale somewhere if you look hard enough

[cool-RR]

Thanks MTManiac. I looked at the datasheet in your link and it looks like M8 (and its relatives) all have an actuation force of 70g, which is way too much for my usecase

[FiskFisk33]

you could take this a few steps further (or many...) and 3d print custom small housings around the existing mx mechanics...
 

[cool-RR]

FiskFisk33: Hehe I hope I won't get that desperate

[MTManiac]

ahhh gotcha, well if you are looking for a low actuation force and small form factor
what about scissor switch keys from a laptop?
you can find a replacement laptop keyboard pretty cheap on e-bay to harvest the switches from

[cool-RR]

Hmm, interesting suggestion. But I rather stick to keys I know I can buy whatever quantity I want in the future. Any idea whether these are sold anywhere?